Study On Preparation And Application In Selective Laser Sintering Of Polypropylene Powders

The competitive power of Rapid Prototyping (RP) is a kind of high-tech manufacturing technology based on material deposition method. One important branch of RP is selective laser sintering (SLS), which has attracted increasing attention. One of the research key points in this field is sintering raw materials. This paper developed several kinds of Polypropylene (PP) powders applied in selective laser sintering.Polypropylene powders were prepared from polypropylene particles with solvent precipitation method. The type of solvent and precipitation solvent, the amount of precipitation solvent and the stirring rate on the yield and bulk density of the powders were studied in order to determine the best condition. The results showed that, when the solvent was toluene, the precipitation solvent was ethanol, the Stirring rate was 300r/min, the optimum yields and the maximum bulk density was got. The best yield was 62%, the maximum accumulation area was 0.224g/cm3.The morphology of the polypropylene powder was improved through the program temperature controlled method. Polypropylene powders prepared by the improved process had compact structure, smooth surface and good sphericity.Polypropylene reinforced composite powders were prepared with the program temperature controlled method by nano-TiO2 particles. The results showed that, with the increasing of the mass fraction of the nano-TiO2 particles, the flexural strength and the flexural modulus firstly increased and then decrease, the impact strength firstly increased and then hold the same; with the increasing of the mass fraction of KH-560, the flexural strength, the flexural modulus and the impact strength firstly increased and then decreased. When the content of TiO2 nanoparticles was 2%, the coupling agent KH-560 was 5%, the best enhancement was got, the scanning electron micrographs showed the crack spread out into a dimple.To solve the shortage of the program temperature controlled method, induced sphericallization method was used to prepare polypropylene microspheres from irregular paticle shape PP. The product of spherical particles getting from this way had regular shape and high sphericity. The average partical size reduced from 24.2 microns of the row powder to 17.5 microns, the bulk density rised from 0.426g/cm3 to 0.518g/cm3, melt flow rate rised from 9.75g/10min to 11.02g/10min, and the accumulation angle reduced from (45.4±1.1)°to (33.0±0.6)°.